Ecology, Ecophysiology and Morpho-colorimetric analysis of wild grapevines populations of Sardinia and relationships with some autochthonous cultivars

Sardinia, with a surface of 24.084 Km2, is the second largest island in the Mediterranean Sea and represents an interesting laboratory, from biological, historical and cultural perspectives, where studies on ecology, ecophysiology and morpho-colorimetric analysis of wild grapevines populations and relationships with some autochthonous cultivars can be carried out. The peculiar insular condition of Sardinia and the large population of wild grapevine coenosis distributed in the whole island, allowed the local inhabitants to develop independent domestication processes. Infact, the wine heritage in Sardinia consists of 210 cultivars. Among these cultivars, 151 are considered as local true varieties and the result of different events, such as the direct domestication of wild grape, crosses between local varieties and the importation of agricultural techniques and cultivars from different ethnic groups that colonised the Island. The remaining 69 varieties can be considered as false attributions (synonyms and/or homonyms) due to the existence of different dialects within the same territory. The observations made in the field in order to detect the presence of young seedlings in the various island populations confirm that the germination period ranges from February to May and at the same time, the germination phenology limits the species distribution, in Sardinia, along riverbanks or colluvial sites of hilly humid slopes (as in most wild grapevine populations found in Europe) where seedlings can grow even during the dry summer conditions, suggesting a phenotypic adaptation to different microclimates. Through the measurement of 113 morpho-colorimetric discriminant parameters on seeds, of which: 33 coming from morpho-colorimetric measurements and 80 coming from the EFDs method we have obtained some statistical classifiers capable to identify, classify the studied cultivars of Vitis vinifera L. subsp. vinifera and to compare them with some wild populations of Vitis vinifera L. subsp. sylvestris (C.C. Gmel) Hegi and some archaeological remains of seeds founded in Sardinia. The use of 93 morphological parameters in the study of the archaeological seeds found in the prenuragic and nuragic site of Sa Osa has permitted their classification as white grapes for dessert wine, still today cultivated under the name of Vernaccia. Moreover, the image analysis technique has been used to investigate the various groups of synonymy and homonymy previously proposed on the basis of the Simple Sequence Repeat (SSR) marker providing high percentage values of correct identification of each group and showing a certain correspondence to the phenotypic seed characters- This results simultaneously suggests some potential modifications to the proposed groupings.